Obtaining Mym

How does one get Mym? Is she’s summonable or do I have to do something to get her?

Gala adventurers can only be summoned in Gala banners. They happen every 2 months, next one should be near the end of July. But only the new unit gets an increased rate so it’s quite hard to get an old one :frowning_face:
https://dragalialost.gamepedia.com/Gala_Dragalia_Showcase
Maybe there’ll be a better way in the future.